Safety device for fuses



1949- R. e. FERRIS ET AL 2,480,563

SAFETY DEVICE FOR FUSES Filed Sept. 4, 1943 \&

' \NVENTORS 0 JAMES 0; JORDAN BY ROBRT G. FER/5 I v I 370 135 390 50 380 X250 TTORNEY housing to secure the plate against rotation relative to the housing and the can.

The plate 25 serves as a guide for a safety gate 3|] which is generally T-shaped, the head 3| of the gate being disposed in the recess 26, and the stem 32 of the gate fitting closely in the slot 21. A weight 33, made of lead, or the like, is secured in a transverse bore in the gate head 3| so that in the normal or innermost position of the gate, the weight is offset from the axis of the can I. It will be observed that when the gate 30 is in its innermost position in plate 25, a substantial clearance is provided between the gate head 3| and the inner wall of housing 2 I, so that the gate is adapted to move outwardly under the action of centrifugal force incident to rotation of the projectile and the can It. Near its inner end, the stem 32 of the gate has a transverse opening for receiving a tetryl charge 34 which, in the innerrigost position of the gate, is offset from the charge A second plate a is seated in the housing 2| on the front face of the guide plate 25 and serves as a guide for a gate 39a. The guide plate 25a and the gate a are similar to the plate 25 and gate 30, respectively, and therefore, a detailed description of them is unnecessary. However, the guide plate 25a is disposed in housing 2| so that its slot 21a and recess 26a are in diametrically opposed relation to the slot 21 and recess 26 of the adjacentjplate 25; Accordingly, the gate 35a. is movable outwardly in a direction opposite to the direction of movement of gate 30, as will be apparent from a comparison of Figs. 2 and 3. The plates 25, 25a and their corresponding gates 30, 3011 are held in the housing 2| against the closed end thereof by means of a cover 35 secured in the open end of the housing, the cover having an axial opening aligned with the azide charge l2.

It will be observed that when the gate 30a is in its innermost position, its tetryl charge 34a is offset radially from the charge l2. Accordingly, in the normal positions of the parts, the tetryl charge 22 is separated from the azide charge |2 by the stems of both of the gates 30 and 36a, so that any accidental explosion of the charge !2 is efiectively blocked and prevented from reaching the charge 22 and the booster H.

In order to lock the gates 30 and 30a in their inner or blocking positions, we provide detents 31 and 31a mounted in transverse bores 38 and 38a, respectively, in plates 25 and 25a. The detents 31 and 31a have reduced inner end portions which normally fit into sockets 39 and 39a. in the gate stems 32 and 32a, respectively, the detents being normally held in the sockets by leaf springs 40 and 40a, respectively, mounted in recessed portions of the guide plates. The springs 40 and 40a are of sufficient strength to prevent withdrawal of the detents from the gate sockets 39 and 39a during handling of the projectile.

The operation of the device is as follows: Prior to firing the projectile, the gates 30 and 30a are locked in their innermost positions by detents 31 and 31a, respectively, so that each gate presents a solid portion of its stem in alignment with the charges I2 and 22. However, when the projectile is fired from a gun, centrifugal force incident to rotation of the projectile causes detents 31 and 31a to move outwardly against the action of springs and 40a, with the result that the detents are withdrawn from the sockets 39, 39a and the gates are released. Thereupon, the action of centrifugal force moves the gates 30 and 30a outwardly but in opposite directions in their respective plates 25 and 25a, each gate being guided in its outward movement by the recess and slot 26, 21 in its guide plate. The outward movement of the gates is arrested when their heads 3|, 3| a engage the side wall of housing 2|, and with the gates in their outermost positions, their respective charges 34, 34a are in alignment with each other and with the charges l2 and 22. That is, when the gates move outwardly under centrifugal force, as seen in Fig. 1, the charge 34 of gate 30 moves downwardly into alignment with the adjacent charge 22 in the housing, and the charge 34a in gate 30a. moves upwardly into alignment with the. adjacent charge I2 in the squib block, the gates being maintained in these positions by centrifugal force as the projectile rotates. Thus, when the squid I4 is detonated electrically through the wiring l4a, it fires the booster through the charges l2, 34a, 34 and 22, and the booster detonates the main charge (not shown) in the projectile. The charge 34 in the gate adjacent booster I! should 'be made of tetryl or other insensitive explosive, while thecharge 34a in the gate adja cent the squib block II should be made of lead azide or-other sensitive explosive. In this connection, it has been found that when an azide charge 34a is used, there is no need for the azide charge H in the squib block. In other words, an azide charge should be placed between the squib and the tetrylcharge 34 in the rear gate 30, but this charge may be placed either in the squib block as shown at l2, or in the front gate 30a. I

vIt will be apparentthat the safety device of our invention issimple and compact in construction and employs relatively .few moving parts. By reason of the double gate assembly in the housing 2|, the device has ahigh factor of safety. and may besubjected to roughhandling without arming .the fuze. An important feature of our invention is that the device will operate satisfactorily even though its axis is offset-from the axis of rotation of the projectile as much as one-eighth of an inch.

Weclaim: In a fuze mechanism for use in a spinning pro jectile, the combination with a cylindrical housing, apair of guide plates each having a centering lug engaging an inner groove of the housing, and said plates each fashioned with a diametrical slot, each said slot having a transverse recess, of a pair of charge-carrying gates each having a crosshead formed with a transverse bore, a weight in the bore, said gates movable in the slots and recesses under centrifugal force in opposite directions for aligning an initially, interrupted explosive train, and means for holding the gates in initial positions and operable. under centrifugal force for releasing the gates.

ROBERT G. FERRIS. JAMES D. JORDAN.'

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS' 

